The present invention is related to brake cylinder pressure retainer valves for railway cars and particularly to a plastic type retainer valve.
Freight cars employing direct release brakes have long employed a brake cylinder pressure retainer valve to selectively control the release of the car brakes independently of the car control valve when descending long grades, in order to maintain a limited braking force during a brake release, while the brake pipe and associated reservoirs are being recharged in preparation for a subsequent brake application.
The standard FB-3 Retainer Valve presently supplied to the railroads is a three-position, manually operated valve to which the brake cylinder exhaust pipe is connected. In the "direct" exhaust position, the brake cylinder pressure is completely released unrestricted, in the "slow direct" exhaust setting, the brake cylinder pressure is released at a restricted rate, and in the "high pressure" retention setting, the brake cylinder pressure is released unrestricted until such time as the pressure is reduced to approximately 20 psi, and is then retained at this reduced pressure. The operating components of this valve are embodied in a cast iron body and provide such desirable features as leakage free operation for an extended service life; ease of handle movement; cartridge assembly replacement for simple and easy maintenance; and mounting on a semi-permanent pipe bracket.